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Cossard A, Stam K, Smets A, Jossin Y. MKL/SRF and Bcl6 mutual transcriptional repression safeguards the fate and positioning of neocortical progenitor cells mediated by RhoA. SCIENCE ADVANCES 2023; 9:eadd0676. [PMID: 37967194 PMCID: PMC10651131 DOI: 10.1126/sciadv.add0676] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2022] [Accepted: 10/16/2023] [Indexed: 11/17/2023]
Abstract
During embryogenesis, multiple intricate and intertwined cellular signaling pathways coordinate cell behavior. Their slightest alterations can have dramatic consequences for the cells and the organs they form. The transcriptional repressor Bcl6 was recently found as important for brain development. However, its regulation and integration with other signals is unknown. Using in vivo functional approaches combined with molecular mechanistic analysis, we identified a reciprocal regulatory loop between B cell lymphoma 6 (Bcl6) and the RhoA-regulated transcriptional complex megakaryoblastic leukemia/serum response factor (MKL/SRF). We show that Bcl6 physically interacts with MKL/SRF, resulting in a down-regulation of the transcriptional activity of both Bcl6 and MKL/SRF. This molecular cross-talk is essential for the control of proliferation, neurogenesis, and spatial positioning of neural progenitors. Overall, our data highlight a regulatory mechanism that controls neuronal production and neocortical development and reveal an MKL/SRF and Bcl6 interaction that may have broader implications in other physiological functions and in diseases.
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Affiliation(s)
- Alexia Cossard
- Laboratory of Mammalian Development and Cell Biology, Institute of Neuroscience, Université Catholique de Louvain, Brussels 1200, Belgium
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2
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González B, Aldea M, Cullen PJ. Chaperone-Dependent Degradation of Cdc42 Promotes Cell Polarity and Shields the Protein from Aggregation. Mol Cell Biol 2023; 43:200-222. [PMID: 37114947 PMCID: PMC10184603 DOI: 10.1080/10985549.2023.2198171] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 03/02/2023] [Accepted: 03/06/2023] [Indexed: 04/29/2023] Open
Abstract
Rho GTPases are global regulators of cell polarity and signaling. By exploring the turnover regulation of the yeast Rho GTPase Cdc42p, we identified new regulatory features surrounding the stability of the protein. We specifically show that Cdc42p is degraded at 37 °C by chaperones through lysine residues located in the C-terminus of the protein. Cdc42p turnover at 37 °C occurred by the 26S proteasome in an ESCRT-dependent manner in the lysosome/vacuole. By analyzing versions of Cdc42p that were defective for turnover, we show that turnover at 37 °C promoted cell polarity but was defective for sensitivity to mating pheromone, presumably mediated through a Cdc42p-dependent MAP kinase pathway. We also identified one residue (K16) in the P-loop of the protein that was critical for Cdc42p stability. Accumulation of Cdc42pK16R in some contexts led to the formation of protein aggregates, which were enriched in aging mother cells and cells undergoing proteostatic stress. Our study uncovers new aspects of protein turnover regulation of a Rho-type GTPase that may extend to other systems. Moreover, residues identified here that mediate Cdc42p turnover correlate with several human diseases, which may suggest that turnover regulation of Cdc42p is important to aspects of human health.
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Affiliation(s)
- Beatriz González
- Department of Biological Sciences, State University of New York at Buffalo, New York, USA
| | - Martí Aldea
- Molecular Biology Institute of Barcelona (IBMB), CSIC, Barcelona, Spain
| | - Paul J. Cullen
- Department of Biological Sciences, State University of New York at Buffalo, New York, USA
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3
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Wirth A, Ponimaskin E. Lipidation of small GTPase Cdc42 as regulator of its physiological and pathophysiological functions. Front Physiol 2023; 13:1088840. [PMID: 36699687 PMCID: PMC9868626 DOI: 10.3389/fphys.2022.1088840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2022] [Accepted: 12/26/2022] [Indexed: 01/11/2023] Open
Abstract
The protein cell division cycle 42 (Cdc42) is a small GTPase of the Rho family regulating a plethora of physiological functions in a tissue, cell and subcellular-specific manner via participating in multiple signaling pathways. Since the corresponding signaling hubs are mainly organized along the cellular membranes, cytosolic proteins like Cdc42 need to be properly targeted and held at the membrane. Here, lipid modifications come into play: Cdc42 can be associated with membranes by different lipid anchors including prenylation (Cdc42-prenyl) and palmitoylation (Cdc42-palm). While Cdc42-prenyl is ubiquitously expressed, Cdc42-palm splicing variant in mainly expressed in the brain. Mechanisms underlying Cdc42 lipidation as well as its regulation are the main topic of this review. Furthermore, we will discuss the functional importance of Cdc42 lipid modifications with the focus on the role of different lipids in regulating defined Cdc42 functions. Finally, we will provide an overview of the possible implementation of Cdc42 lipidation in pathological conditions and different diseases.
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4
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Rather IIG, Behl T, Sehgal A, Singh S, Sharma N, Sharma A, Bhatia S, Al-Harrasi A, Khan N, Khan H, Bungau S. Exploration of potential role of Rho GTPase in nicotine dependence-induced withdrawal syndrome in mice. ENVIRONMENTAL SCIENCE AND POLLUTION RESEARCH INTERNATIONAL 2022; 29:17417-17424. [PMID: 34665416 DOI: 10.1007/s11356-021-17059-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2021] [Accepted: 10/11/2021] [Indexed: 06/13/2023]
Abstract
The RhoA gene showed an important genotypic association with nicotine dependence and smoking initiation. The current study aims to investigate the effect of the Rho GTPase inhibitor ML141 in the progression of nicotine dependence in a mice model of precipitated nicotine withdrawal syndrome by mecamylamine.The experimental procedure involved administration of 2.5 mg/kg nicotine dissolved in normal saline subcutaneously (s.c) four times a day consecutively for 7 days and last single dose in the morning on 8th day. ML-141 was dissolved in dimethyl sulfoxide (DMSO) and was administered daily with nicotine as corrective treatment at a dose of 1,5 and 10 mg/kg (p < 0.05). An injection of 3 mg/kg of mecamylamine intraperitoneal (ip) was given an hour later than the last nicotine dose on the day 8 to precipitate withdrawal of nicotine and withdrawal severity was assessed by measuring hyperalgesia, piloerection, jumping frequency, tremors, and withdrawal severity score (WSS). Various behavioural changes such as hyperalgesia, piloerection, jumping frequency, and tremors were monitored and WSS was calculated. ML-141 a selective Rho GTPase inhibitor was found to show dose-dependent effect on all these parameters. Inhibition of Rho GTPase was found to reduce the severity of withdrawal syndrome; therefore, it can be concluded that Rho GTPase would serve as a suitable biological target by regulating the reward system in brain and could be used as new target for drug discovery.
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Affiliation(s)
| | - Tapan Behl
- Chitkara College of Pharmacy, Chitkara University, Punjab, India.
| | - Aayush Sehgal
- Chitkara College of Pharmacy, Chitkara University, Punjab, India
| | - Sukhbir Singh
- Chitkara College of Pharmacy, Chitkara University, Punjab, India
| | - Neelam Sharma
- Chitkara College of Pharmacy, Chitkara University, Punjab, India
| | - Aditi Sharma
- School of Pharmaceutical Sciences, Shoolini University, Solan, Himachal Pradesh, India
| | - Saurabh Bhatia
- School of Health Science, University of Petroleum and Energy Studies, Dehradun, Uttarakhand, India
- Natural & Medical Sciences Research Centre, University of Nizwa, Birkat Al Mauz, Nizwa, Oman
| | - Ahmed Al-Harrasi
- Natural & Medical Sciences Research Centre, University of Nizwa, Birkat Al Mauz, Nizwa, Oman
| | | | - Haroon Khan
- Department of Pharmacy, Abdul Wali Khan University Mardan, Mardan, Pakistan
| | - Simona Bungau
- Department of Pharmacy, Faculty of Medicine and Pharmacy, University of Oradea, Oradea, Romania
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5
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STK25 and MST3 Have Overlapping Roles to Regulate Rho GTPases during Cortical Development. J Neurosci 2021; 41:8887-8903. [PMID: 34518307 DOI: 10.1523/jneurosci.0523-21.2021] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2021] [Revised: 08/13/2021] [Accepted: 09/06/2021] [Indexed: 11/21/2022] Open
Abstract
Precise control of neuronal migration is required for the laminar organization of the neocortex and critical for brain function. We previously reported that the acute disruption of the Stk25 gene (Stk25 conditional knock-out; cKO) during mouse embryogenesis causes anomalous neuronal migration in the neocortex, but paradoxically the Stk25 cKO did not have a cortical phenotype, suggesting some forms of compensation exist. In this study, we report that MST3, another member of the GCKIII subgroup of the Ste20-like kinase family, compensates for loss of Stk25 and vice versa with sex independent manner. MST3 overexpression rescued neuronal migration deficit and abnormal axonogenesis in Stk25 cKO brains. Mechanistically, STK25 leads to Rac1 activation and reduced RhoA levels in the developing brain, both of which are required to fully restore neuronal migration in the Stk25 cKO brain. Abnormal migration phenotypes are also rescued by overexpression of Bacurd1and Cul3, which target RhoA for degradation, and activate Rac1. This study reveals that MST3 upregulation is capable of rescuing acute Stk25 deficiency and resolves details of signaling downstream STK25 required for corticogenesis both common to and distinct from MST3 signaling.SIGNIFICANCE STATEMENT Proper neuronal migration during cortical development is required for normal neuronal function. Here, we show that STK25 and MST3 kinases regulate neuronal migration and polarization in a mutually compensatory manner. Furthermore, STK25 balances Rac1 activity and RhoA level through forming complexes with α-PIX and β-PIX, GTPase regulatory enzymes, and Cullin3-Bacurd1/Kctd13, a pair of RhoA ubiquitination molecules in a kinase activity-independent manner. Our findings demonstrate the importance of overlapping and unique roles of STK25 and MST3 to regulate Rho GTPase activities in cortical development.
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Jossin Y. Molecular mechanisms of cell polarity in a range of model systems and in migrating neurons. Mol Cell Neurosci 2020; 106:103503. [PMID: 32485296 DOI: 10.1016/j.mcn.2020.103503] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2020] [Revised: 04/20/2020] [Accepted: 05/23/2020] [Indexed: 01/09/2023] Open
Abstract
Cell polarity is defined as the asymmetric distribution of cellular components along an axis. Most cells, from the simplest single-cell organisms to highly specialized mammalian cells, are polarized and use similar mechanisms to generate and maintain polarity. Cell polarity is important for cells to migrate, form tissues, and coordinate activities. During development of the mammalian cerebral cortex, cell polarity is essential for neurogenesis and for the migration of newborn but as-yet undifferentiated neurons. These oriented migrations include both the radial migration of excitatory projection neurons and the tangential migration of inhibitory interneurons. In this review, I will first describe the development of the cerebral cortex, as revealed at the cellular level. I will then define the core molecular mechanisms - the Par/Crb/Scrib polarity complexes, small GTPases, the actin and microtubule cytoskeletons, and phosphoinositides/PI3K signaling - that are required for asymmetric cell division, apico-basal and front-rear polarity in model systems, including C elegans zygote, Drosophila embryos and cultured mammalian cells. As I go through each core mechanism I will explain what is known about its importance in radial and tangential migration in the developing mammalian cerebral cortex.
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Affiliation(s)
- Yves Jossin
- Laboratory of Mammalian Development & Cell Biology, Institute of Neuroscience, Université Catholique de Louvain, Brussels, Belgium.
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Fray MA, Charpentier JC, Sylvain NR, Seminario MC, Bunnell SC. Vav2 lacks Ca 2+ entry-promoting scaffolding functions unique to Vav1 and inhibits T cell activation via Cdc42. J Cell Sci 2020; 133:jcs238337. [PMID: 31974114 PMCID: PMC7075049 DOI: 10.1242/jcs.238337] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2019] [Accepted: 01/06/2020] [Indexed: 12/16/2022] Open
Abstract
Vav family guanine nucleotide exchange factors (GEFs) are essential regulators of immune function. Despite their structural similarity, Vav1 promotes and Vav2 opposes T cell receptor (TCR)-induced Ca2+ entry. By using a Vav1-deficient Jurkat T cell line, we find that Vav1 facilitates Ca2+ entry via non-catalytic scaffolding functions that are encoded by the catalytic core of Vav1 and flanking linker regions. We implicate, in this scaffolding function, a previously undescribed polybasic motif that is strictly conserved in Vav1 and absent from Vav2 in tetrapods. Conversely, the catalytic activity of Vav2 contributes to the suppression of TCR-mediated Ca2+ entry. By performing an in vivo 'GEF trapping' assay in intact cells, we demonstrate that Cdc42 interacts with the catalytic surface of Vav2 but not Vav1, and that Vav1 discriminates Cdc42 from Rac1 via F56 (W56 in Rac1). Finally, the Cdc42-specific inhibitor ZCL278 and the shRNA-mediated suppression of Cdc42 each prevent the inhibition of TCR-induced Ca2+ entry by Vav2. These findings define stark differences in the functions of Vav1 and Vav2, and provide an explanation for the differential usage of these Vav isoforms by immune subpopulations.
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Affiliation(s)
- Michael A Fray
- Program in Immunology, Department of Immunology, Tufts University School of Medicine, Boston, MA 02111, USA
| | - John C Charpentier
- Department of Biology, University of Massachusetts Boston, Boston, MA 02125, USA
| | - Nicholas R Sylvain
- Program in Immunology, Department of Immunology, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Maria-Cristina Seminario
- Program in Immunology, Department of Immunology, Tufts University School of Medicine, Boston, MA 02111, USA
| | - Stephen C Bunnell
- Program in Immunology, Department of Immunology, Tufts University School of Medicine, Boston, MA 02111, USA
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Endo M, Druso JE, Cerione RA. The two splice variant forms of Cdc42 exert distinct and essential functions in neurogenesis. J Biol Chem 2020; 295:4498-4512. [PMID: 32071086 DOI: 10.1074/jbc.ra119.011837] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/08/2019] [Revised: 01/31/2020] [Indexed: 12/29/2022] Open
Abstract
The small GTPase cell division cycle 42 (CDC42) plays essential roles in neurogenesis and brain development. Previously, using murine embryonic P19 cells as a model system, we showed that CDC42 stimulates mTOR complex 1 (mTORC1) activity and thereby up-regulates transcription factors required for the formation of neural progenitor cells. However, paradoxically, although endogenous CDC42 is required for both the initial transition of undifferentiated P19 cells to neural progenitors and their ultimate terminal differentiation into neurons, ectopic CDC42 overexpression promotes only the first stage of neurogenesis (i.e. the formation of neuroprogenitors) and not the second phase (differentiation into neurons). Here, using both P19 cells and mouse embryonic stem cells, we resolve this paradox, demonstrating that two splice variants of CDC42, differing only in nine amino acid residues in their very C-terminal regions, play distinct roles in neurogenesis. We found that a CDC42 splice variant that has a ubiquitous tissue distribution, termed here as CDC42u, specifically drives the formation of neuroprogenitor cells, whereas a brain-specific CDC42 variant, CDC42b, is essential for promoting the transition of neuroprogenitor cells to neurons. We further show that the specific roles of CDC42u and CDC42b in neurogenesis are due to their opposing effects on mTORC1 activity. Specifically, CDC42u stimulated mTORC1 activity and thereby induced neuroprogenitor formation, whereas CDC42b worked together with activated CDC42-associated kinase (ACK) in down-regulating mTOR expression and promoting neuronal differentiation. These findings highlight the remarkable functional specificities of two highly similar CDC42 splice variants in regulating distinct stages of neurogenesis.
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Affiliation(s)
- Makoto Endo
- Department of Molecular Medicine, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853
| | - Joseph E Druso
- Department of Molecular Medicine, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853
| | - Richard A Cerione
- Department of Molecular Medicine, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853 .,Department of Chemistry and Chemical Biology, Baker Laboratory, Cornell University, Ithaca, New York 14853
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Xu Z, Chen Y, Chen Y. Spatiotemporal Regulation of Rho GTPases in Neuronal Migration. Cells 2019; 8:cells8060568. [PMID: 31185627 PMCID: PMC6627650 DOI: 10.3390/cells8060568] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2019] [Revised: 06/01/2019] [Accepted: 06/04/2019] [Indexed: 12/17/2022] Open
Abstract
Neuronal migration is essential for the orchestration of brain development and involves several contiguous steps: interkinetic nuclear movement (INM), multipolar–bipolar transition, locomotion, and translocation. Growing evidence suggests that Rho GTPases, including RhoA, Rac, Cdc42, and the atypical Rnd members, play critical roles in neuronal migration by regulating both actin and microtubule cytoskeletal components. This review focuses on the spatiotemporal-specific regulation of Rho GTPases as well as their regulators and effectors in distinct steps during the neuronal migration process. Their roles in bridging extracellular signals and cytoskeletal dynamics to provide optimal structural support to the migrating neurons will also be discussed.
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Affiliation(s)
- Zhenyan Xu
- The Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen 518055, Guangdong, China.
| | - Yuewen Chen
- The Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen 518055, Guangdong, China.
- Guangdong Provincial Key Laboratory of Brain Science, Disease and Drug Development, HKUST Shenzhen Research Institute, Shenzhen 518057, Guangdong, China.
| | - Yu Chen
- The Brain Cognition and Brain Disease Institute, Shenzhen Institutes of Advanced Technology, Chinese Academy of Sciences, Shenzhen-Hong Kong Institute of Brain Science-Shenzhen Fundamental Research Institutions, Shenzhen 518055, Guangdong, China.
- Guangdong Provincial Key Laboratory of Brain Science, Disease and Drug Development, HKUST Shenzhen Research Institute, Shenzhen 518057, Guangdong, China.
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Chen YA, Lu IL, Tsai JW. Contactin-1/F3 Regulates Neuronal Migration and Morphogenesis Through Modulating RhoA Activity. Front Mol Neurosci 2018; 11:422. [PMID: 30515076 PMCID: PMC6255823 DOI: 10.3389/fnmol.2018.00422] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2018] [Accepted: 10/30/2018] [Indexed: 01/06/2023] Open
Abstract
During neocortical development, newborn neurons migrate along radial fibers from the germinal ventricular zone (VZ) toward the cortical plate (CP) to populate the cerebral cortex. This radial migration requires adhesion activities between neurons and radial fibers; however, past research has identified only a limited number of adhesion molecules involved in this process. Contactin-1/F3 (Cntn1), a cell adhesion molecule expressed in the developing nervous system is essential for many key developmental events including neural cell adhesion, neurite outgrowth, axon guidance and myelination. However, the potential role of Cntn1 in neuronal migration during cortical development has not been investigated. Here we used in utero electroporation to introduce short hairpin RNA (shRNA) to knock down (KD) Cntn1 in neural stem cells in vivo. We found that Cntn1 KD led to a delay in neuronal migration. The arrested cells presented abnormal morphology in their leading process and more multipolar cells were observed in the deep layers of the brain, suggestive of dysregulation in process formation. Intriguingly, Cntn1 KD also resulted in upregulation of RhoA, a negative regulator for neuronal migration. Interference of RhoA by expression of the dominant-negative RhoAN19 partially rescued the neuronal migration defects caused by Cntn1 KD. Our results showed that Cntn1 is a novel adhesion protein that is essential for neuronal migration and regulates process formation of newborn cortical neurons through modulating RhoA signaling pathway.
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Affiliation(s)
- Yi-An Chen
- Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan
| | - I-Ling Lu
- Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan
| | - Jin-Wu Tsai
- Institute of Brain Science, National Yang-Ming University, Taipei, Taiwan.,Brain Research Center, National Yang-Ming University, Taipei, Taiwan.,Biophotonics and Molecular Imaging Research Center, National Yang-Ming University, Taipei, Taiwan
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Rab35 Functions in Axon Elongation Are Regulated by P53-Related Protein Kinase in a Mechanism That Involves Rab35 Protein Degradation and the Microtubule-Associated Protein 1B. J Neurosci 2017; 36:7298-313. [PMID: 27383602 DOI: 10.1523/jneurosci.4064-15.2016] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2015] [Accepted: 05/30/2016] [Indexed: 12/20/2022] Open
Abstract
UNLABELLED Rab35 is a key protein for cargo loading in the recycling endosome. In neuronal immortalized cells, Rab35 promotes neurite differentiation. Here we describe that Rab35 favors axon elongation in rat primary neurons in an activity-dependent manner. In addition, we show that the p53-related protein kinase (PRPK) negatively regulates axonal elongation by reducing Rab35 protein levels through the ubiquitin-proteasome degradation pathway. PRPK-induced Rab35 degradation is regulated by its interaction with microtubule-associated protein 1B (MAP1B), a microtubule stabilizing binding protein essential for axon elongation. Consistently, axon defects found in MAP1B knock-out neurons were reversed by Rab35 overexpression or PRPK inactivation suggesting an epistatic relationship among these proteins. These results define a novel mechanism to support axonal elongation, by which MAP1B prevents PRPK-induced Rab35 degradation. Such a mechanism allows Rab35-mediated axonal elongation and connects the regulation of actin dynamics with membrane trafficking. In addition, our study reveals for the first time that the ubiquitin-proteasome degradation pathway regulates a Rab GTPase. SIGNIFICANCE STATEMENT Rab35 is required for axonal outgrowth. We define that its protein levels are negatively regulated by p53-related protein kinase (PRPK). We show that microtubule-associated protein 1B (MAP1B) interacts with PRPK, preventing PRPK-dependent Rab35 proteasome degradation. We demonstrate that Rab35 regulates Cdc42 activity in neurons. This is the first evidence showing that a Rab protein is regulated by degradation dependent on the ubiquitin-proteasome system.
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Liu F, Guo H, Ou M, Hou X, Sun G, Gong W, Jing H, Tan Q, Xue W, Dai Y, Sui W. ARHGAP4 mutated in a Chinese intellectually challenged family. Gene 2015; 578:205-9. [PMID: 26707211 DOI: 10.1016/j.gene.2015.12.035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Revised: 12/05/2015] [Accepted: 12/11/2015] [Indexed: 10/22/2022]
Abstract
OBJECTIVE Mental retardation is characterized by lower intelligence compared to the average intelligence of persons the same age. These patients have low adaptive capacity acquired by society. The genetic factors of causing MR include monogenic disease, chromosome structural aberration, and chromosome number aberration and so on. We explored the cause of a Chinese family suffering from mental retardation. METHODS We used karyotyping technology to determine the karyotype of the proband, and we used FISH to verify the result of the karyotyping. We used whole-exome sequencing to identify the disease-causing gene and used Sanger sequencing to verify the result of whole-exome sequencing to assess the family's gene expression. RESULTS The G-banding of the karyotype revealed that the patient's karyotype is 46, XY. FISH revealed that the patient does not have a trisomy syndrome. The karyotype of the proband is normal. Using whole-exome sequencing, we identified 108,767 variants in the exome gene of the patient, including 101,787 SNPs and 6980 InDels. Combining clinical information and bioinformatics analysis, including databases filtering and SIFT analysis, we found ARHGAP4 in X chromosome was candidate MR disease-causing gene. PCR and Sanger sequencing results were consistent with whole-exome sequencing. ARHGAP4 (T491M) mutation was present in the genome of the proband and his mother is a carrier, while his father, sister, and brother do not carry this mutation. CONCLUSION According to clinical information, whole-exome sequencing results and Sanger verification results, ARHGAP4 (T491M) mutation may be disease-causing gene of the MR patient. The relation between ARHGAP4 mutation and MR clinical characteristic is needed to be illuminated with participation of more MR patients.
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Affiliation(s)
- Fuhua Liu
- Nephrology Department of Guilin, 181 St Hospital, Guangxi Key Laboratory of Metabolic Diseases Research, 541002 Guilin, Guangxi, China; College of Life Science, Guangxi Normal University, 541004 Guilin, Guangxi, China
| | - Hui Guo
- Clinical Medical Research Center, the Second Clinical Medical College of Jinan University, Shenzhen People's Hospital, 518020, Shenzhen, Guangdong, China
| | - Minglin Ou
- Nephrology Department of Guilin, 181 St Hospital, Guangxi Key Laboratory of Metabolic Diseases Research, 541002 Guilin, Guangxi, China
| | - Xianliang Hou
- Nephrology Department of Guilin, 181 St Hospital, Guangxi Key Laboratory of Metabolic Diseases Research, 541002 Guilin, Guangxi, China
| | - Guoping Sun
- Lab. Center, Shenzhen Pingshan People's Hospital, Shenzhen, Guangdong 518118, China
| | - Weiwei Gong
- Nephrology Department of Guilin, 181 St Hospital, Guangxi Key Laboratory of Metabolic Diseases Research, 541002 Guilin, Guangxi, China
| | - Huanyun Jing
- Nephrology Department of Guilin, 181 St Hospital, Guangxi Key Laboratory of Metabolic Diseases Research, 541002 Guilin, Guangxi, China
| | - Qiupei Tan
- Nephrology Department of Guilin, 181 St Hospital, Guangxi Key Laboratory of Metabolic Diseases Research, 541002 Guilin, Guangxi, China
| | - Wen Xue
- Nephrology Department of Guilin, 181 St Hospital, Guangxi Key Laboratory of Metabolic Diseases Research, 541002 Guilin, Guangxi, China
| | - Yong Dai
- Clinical Medical Research Center, the Second Clinical Medical College of Jinan University, Shenzhen People's Hospital, 518020, Shenzhen, Guangdong, China.
| | - Weiguo Sui
- Nephrology Department of Guilin, 181 St Hospital, Guangxi Key Laboratory of Metabolic Diseases Research, 541002 Guilin, Guangxi, China.
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Azzarelli R, Kerloch T, Pacary E. Regulation of cerebral cortex development by Rho GTPases: insights from in vivo studies. Front Cell Neurosci 2015; 8:445. [PMID: 25610373 PMCID: PMC4285737 DOI: 10.3389/fncel.2014.00445] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/22/2014] [Accepted: 12/11/2014] [Indexed: 12/31/2022] Open
Abstract
The cerebral cortex is the site of higher human cognitive and motor functions. Histologically, it is organized into six horizontal layers, each containing unique populations of molecularly and functionally distinct excitatory projection neurons and inhibitory interneurons. The stereotyped cellular distribution of cortical neurons is crucial for the formation of functional neural circuits and it is predominantly established during embryonic development. Cortical neuron development is a multiphasic process characterized by sequential steps of neural progenitor proliferation, cell cycle exit, neuroblast migration and neuronal differentiation. This series of events requires an extensive and dynamic remodeling of the cell cytoskeleton at each step of the process. As major regulators of the cytoskeleton, the family of small Rho GTPases has been shown to play essential functions in cerebral cortex development. Here we review in vivo findings that support the contribution of Rho GTPases to cortical projection neuron development and we address their involvement in the etiology of cerebral cortex malformations.
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Affiliation(s)
- Roberta Azzarelli
- Department of Oncology, Hutchison/MRC Research Centre, Cambridge Biomedical Campus, University of Cambridge Cambridge, UK
| | - Thomas Kerloch
- Institut National de la Santé et de la Recherche Médicale U862, Neurocentre Magendie Bordeaux, France ; Institut National de la Santé et de la Recherche Médicale, Physiopathologie de la Plasticité Neuronale, Université de Bordeaux Bordeaux, France
| | - Emilie Pacary
- Institut National de la Santé et de la Recherche Médicale U862, Neurocentre Magendie Bordeaux, France ; Institut National de la Santé et de la Recherche Médicale, Physiopathologie de la Plasticité Neuronale, Université de Bordeaux Bordeaux, France
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14
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Nakamura S, Igarashi M, Kinoshita M, Okano HJ, Okano H. Proposing a new RNA quadruplex structure: j-motif, with possible links to neural development. J Biochem 2014; 155:385-92. [PMID: 24596122 DOI: 10.1093/jb/mvu013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
An RNA-binding protein, hnRNP K, has been studied extensively because of its involvement in neural development through the post-transcriptional regulation of its downstream target genes; however, its binding mode remains unclear. According to structural features of the binding sites, we have presumed the existence of possible unique structures 'j-motifs' that are similar to known i-motifs, the difference being that the initial cluster comprises successive U nucleic acids instead of C. It was suspected that the motifs could be recognized by hnRNP K to regulate the translation levels of target proteins, however, there were virtually no methods to verify their existence except computational methods: regular expression searches and theoretical molecular orbital (MO) calculations. Here, we first show a list of 16 genes having j-motif-like sequences we discovered under refined search conditions. The list was highly related to neural development from both subjective and objective aspects. Additionally, MO calculations revealed the similarity of non-canonical base pairs found in i- and j-motifs qualitatively, leading to a proposal of the possible existence of the j-motifs. When taken into consideration, it was indicated that the j-motifs could be formed and play some role in the neural development.
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Affiliation(s)
- Shingo Nakamura
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa 251-8555; Department of Physiology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582; Department of Science and Technology, Sophia University,7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554; and Division of Regenerative Medicine, Jikei University School of Medicine, 3-25-8 Nishishinbashi, Minato-ku, Tokyo, 105-8461, Japan
| | - Mana Igarashi
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa 251-8555; Department of Physiology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582; Department of Science and Technology, Sophia University,7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554; and Division of Regenerative Medicine, Jikei University School of Medicine, 3-25-8 Nishishinbashi, Minato-ku, Tokyo, 105-8461, JapanPharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa 251-8555; Department of Physiology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582; Department of Science and Technology, Sophia University,7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554; and Division of Regenerative Medicine, Jikei University School of Medicine, 3-25-8 Nishishinbashi, Minato-ku, Tokyo, 105-8461, Japan
| | - Mika Kinoshita
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa 251-8555; Department of Physiology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582; Department of Science and Technology, Sophia University,7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554; and Division of Regenerative Medicine, Jikei University School of Medicine, 3-25-8 Nishishinbashi, Minato-ku, Tokyo, 105-8461, Japan
| | - Hirotaka J Okano
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa 251-8555; Department of Physiology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582; Department of Science and Technology, Sophia University,7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554; and Division of Regenerative Medicine, Jikei University School of Medicine, 3-25-8 Nishishinbashi, Minato-ku, Tokyo, 105-8461, Japan
| | - Hideyuki Okano
- Pharmaceutical Research Division, Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-chome, Fujisawa, Kanagawa 251-8555; Department of Physiology, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582; Department of Science and Technology, Sophia University,7-1 Kioi-cho, Chiyoda-ku, Tokyo 102-8554; and Division of Regenerative Medicine, Jikei University School of Medicine, 3-25-8 Nishishinbashi, Minato-ku, Tokyo, 105-8461, Japan
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15
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Azzarelli R, Pacary E, Garg R, Garcez P, van den Berg D, Riou P, Ridley AJ, Friedel RH, Parsons M, Guillemot F. An antagonistic interaction between PlexinB2 and Rnd3 controls RhoA activity and cortical neuron migration. Nat Commun 2014; 5:3405. [PMID: 24572910 PMCID: PMC3939360 DOI: 10.1038/ncomms4405] [Citation(s) in RCA: 57] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2013] [Accepted: 02/06/2014] [Indexed: 02/06/2023] Open
Abstract
A transcriptional programme initiated by the proneural factors Neurog2 and Ascl1 controls successive steps of neurogenesis in the embryonic cerebral cortex. Previous work has shown that proneural factors also confer a migratory behaviour to cortical neurons by inducing the expression of the small GTP-binding proteins such as Rnd2 and Rnd3. However, the directionality of radial migration suggests that migrating neurons also respond to extracellular signal-regulated pathways. Here we show that the Plexin B2 receptor interacts physically and functionally with Rnd3 and stimulates RhoA activity in migrating cortical neurons. Plexin B2 competes with p190RhoGAP for binding to Rnd3, thus blocking the Rnd3-mediated inhibition of RhoA and also recruits RhoGEFs to directly stimulate RhoA activity. Thus, an interaction between the cell-extrinsic Plexin signalling pathway and the cell-intrinsic Ascl1-Rnd3 pathway determines the level of RhoA activity appropriate for cortical neuron migration.
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Affiliation(s)
- Roberta Azzarelli
- Division of Molecular Neurobiology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
- Present address: Hutchison/MRC Research Centre, University of Cambridge, Box 197, Biomedical Campus, Cambridge CB2 0XZ, UK
| | - Emilie Pacary
- Division of Molecular Neurobiology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
- Present address: INSERM, Neurocentre Magendie, Physiopathologie de la Plasticité Neuronale, U862, Bordeaux F-33000, France or University Bordeaux, Neurocentre Magendie, Physiopathologie de la plasticité neuronale, U862, Bordeaux F-33000, France
| | - Ritu Garg
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK
| | - Patricia Garcez
- Division of Molecular Neurobiology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Debbie van den Berg
- Division of Molecular Neurobiology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
| | - Philippe Riou
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK
- Present address: Protein Phosphorylation Laboratory, Cancer Research UK, London Research Institute, Lincoln's Inn Fields Laboratories, London WC2A 3LY, UK
| | - Anne J. Ridley
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK
| | - Roland H. Friedel
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, 1425 Madison Avenue, New York, New York 10029, USA
| | - Maddy Parsons
- Randall Division of Cell and Molecular Biophysics, King's College London, London SE1 1UL, UK
| | - François Guillemot
- Division of Molecular Neurobiology, MRC National Institute for Medical Research, Mill Hill, London NW7 1AA, UK
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16
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Govek EE, Hatten ME, Van Aelst L. The role of Rho GTPase proteins in CNS neuronal migration. Dev Neurobiol 2011; 71:528-53. [PMID: 21557504 DOI: 10.1002/dneu.20850] [Citation(s) in RCA: 128] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The architectonics of the mammalian brain arise from a remarkable range of directed cell migrations, which orchestrate the emergence of cortical neuronal layers and pattern brain circuitry. At different stages of cortical histogenesis, specific modes of cell motility are essential to the stepwise formation of cortical architecture. These movements range from interkinetic nuclear movements in the ventricular zone, to migrations of early-born, postmitotic polymorphic cells into the preplate, to the radial migration of precursors of cortical output neurons across the thickening cortical wall, and the vast, tangential migrations of interneurons from the basal forebrain into the emerging cortical layers. In all cases, actomyosin motors act in concert with cell adhesion receptor systems to provide the force and traction needed for forward movement. As key regulators of actin and microtubule cytoskeletons, cell polarity, and adhesion, the Rho GTPases play critical roles in CNS neuronal migration. This review will focus on the different types of migration in the developing neocortex and cerebellar cortex, and the role of the Rho GTPases, their regulators and effectors in these CNS migrations, with particular emphasis on their involvement in radial migration.
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Affiliation(s)
- Eve-Ellen Govek
- Laboratory of Developmental Neurobiology, The Rockefeller University, NY 10065, USA
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17
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Leone DP, Srinivasan K, Brakebusch C, McConnell SK. The rho GTPase Rac1 is required for proliferation and survival of progenitors in the developing forebrain. Dev Neurobiol 2010; 70:659-78. [PMID: 20506362 DOI: 10.1002/dneu.20804] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Progenitor cells in the ventricular zone (VZ) and subventricular zone (SVZ) of the developing forebrain give rise to neurons and glial cells, and are characterized by distinct morphologies and proliferative behaviors. The mechanisms that distinguish VZ and SVZ progenitors are not well understood, although the homeodomain transcription factor Cux2 and Cyclin D2, a core component of the cell cycle machinery, are specifically involved in controlling SVZ cell proliferation. Rho GTPases have been implicated in regulating the proliferation, differentiation, and migration of many cell types, and one family member, Cdc42, affects the polarity and proliferation of radial glial cells in the VZ. Here, we show that another family member, Rac1, is required for the normal proliferation and differentiation of SVZ progenitors and for survival of both VZ and SVZ progenitors. A forebrain-specific loss of Rac1 leads to an SVZ-specific reduction in proliferation, a concomitant increase in cell cycle exit, and premature differentiation. In Rac1 mutants, the SVZ and VZ can no longer be delineated, but rather fuse to become a single compact zone of intermingled cells. Cyclin D2 expression, which is normally expressed by both VZ and SVZ progenitors, is reduced in Rac1 mutants, suggesting that the mutant cells differentiate precociously. Rac1-deficient mice can still generate SVZ-derived upper layer neurons, indicating that Rac1 is not required for the acquisition of upper layer neuronal fates, but instead is needed for the normal regulation of proliferation by progenitor cells in the SVZ.
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Affiliation(s)
- Dino P Leone
- Department of Biology, Stanford University, Stanford, California 94305, USA
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18
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Abstract
Actin-rich dendritic spines are the locus of excitatory synaptic transmission and plastic events such as long-term potentiation (LTP). Morphological plasticity of spines accompanies activity-dependent changes in synaptic strength. Several Rho GTPase family members are implicated in regulating neuronal and, in particular, spine structure via actin and the actin-binding protein cofilin. However, despite expression in hippocampus and cortex, its ability to modulate actin-regulatory proteins, and its induction during aging, RhoB has been relatively neglected. We previously demonstrated that LTP is associated with specific RhoB activation. Here, we further examined its role in synaptic function using mice with genetic deletion of the RhoB GTPase (RhoB(-/-) mice). Normal basal synaptic transmission accompanied reduced paired-pulse facilitation and post-tetanic potentiation in the hippocampus of RhoB(-/-) mice. Early phase LTP was significantly reduced in RhoB(-/-) animals, whereas the later phase was unaffected. In wild-type mice (RhoB(+/+)), Western blot analysis of potentiated hippocampus showed significant increases in phosphorylated cofilin relative to nonpotentiated slices, which were dramatically impaired in RhoB(-/-) slices. There was also a deficit in phosphorylated Lim kinase levels in the hippocampus from RhoB(-/-) mice. Morphological analysis suggested that lack of RhoB resulted in increased dendritic branching and decreased spine number. Furthermore, an increase in the proportion of stubby relative to thin spines was observed. Moreover, spines demonstrated increased length along with increased head and neck widths. These data implicate RhoB in cofilin regulation and dendritic and spine morphology, highlighting its importance in synaptic plasticity at a structural and functional level.
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19
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Mathis C, Schröter A, Thallmair M, Schwab ME. Nogo-a regulates neural precursor migration in the embryonic mouse cortex. ACTA ACUST UNITED AC 2010; 20:2380-90. [PMID: 20093372 PMCID: PMC2936797 DOI: 10.1093/cercor/bhp307] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Although Nogo-A has been intensively studied for its inhibitory effect on axonal regeneration in the adult central nervous system, little is known about its function during brain development. In the embryonic mouse cortex, Nogo-A is expressed by radial precursor/glial cells and by tangentially migrating as well as postmigratory neurons. We studied radially migrating neuroblasts in wild-type and Nogo-A knockout (KO) mouse embryos. In vitro analysis showed that Nogo-A and its receptor components NgR, Lingo-1, TROY, and p75 are expressed in cells emigrating from embryonic forebrain–derived neurospheres. Live imaging revealed an increased cell motility when Nogo-A was knocked out or blocked with antibodies. Antibodies blocking NgR or Lingo-1 showed the same motility-enhancing effect supporting a direct role of surface Nogo-A on migration. Bromodeoxyuridine (BrdU) labeling of embryonic day (E)15.5 embryos demonstrated that Nogo-A influences the radial migration of neuronal precursors. At E17.5, the normal transient accumulation of radially migrating precursors within the subventricular zone was not detectable in the Nogo-A KO mouse cortex. At E19, migration to the upper cortical layers was disturbed. These findings suggest that Nogo-A and its receptor complex play a role in the interplay of adhesive and repulsive cell interactions in radial migration during cortical development.
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Affiliation(s)
- Carole Mathis
- Brain Research Institute, University of Zurich and Department of Biology, ETH Zurich, 8057 Zurich, Switzerland
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20
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Gauthier-Fisher A, Lin DC, Greeve M, Kaplan DR, Rottapel R, Miller FD. Lfc and Tctex-1 regulate the genesis of neurons from cortical precursor cells. Nat Neurosci 2009; 12:735-44. [DOI: 10.1038/nn.2339] [Citation(s) in RCA: 73] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2009] [Accepted: 03/31/2009] [Indexed: 12/20/2022]
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21
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Pinto L, Mader MT, Irmler M, Gentilini M, Santoni F, Drechsel D, Blum R, Stahl R, Bulfone A, Malatesta P, Beckers J, Götz M. Prospective isolation of functionally distinct radial glial subtypes--lineage and transcriptome analysis. Mol Cell Neurosci 2008; 38:15-42. [PMID: 18372191 DOI: 10.1016/j.mcn.2008.01.012] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2007] [Accepted: 01/07/2008] [Indexed: 12/18/2022] Open
Abstract
Since the discovery of radial glia as the source of neurons, their heterogeneity in regard to neurogenesis has been described by clonal and time-lapse analysis in vitro. However, the molecular determinants specifying neurogenic radial glia differently from radial glia that mostly self-renew remain ill-defined. Here, we isolated two radial glial subsets that co-exist at mid-neurogenesis in the developing cerebral cortex and their immediate progeny. While one subset generates neurons directly, the other is largely non-neurogenic but also gives rise to Tbr2-positive basal precursors, thereby contributing indirectly to neurogenesis. Isolation of these distinct radial glia subtypes allowed determining interesting differences in their transcriptome. These transcriptomes were also strikingly different from the transcriptome of radial glia isolated at the end of neurogenesis. This analysis therefore identifies, for the first time, the lineage origin of basal progenitors and the molecular differences of this lineage in comparison to directly neurogenic and gliogenic radial glia.
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Affiliation(s)
- Luisa Pinto
- Helmholtz Zentrum München, German Research Center for Environmental Health (GmbH), Institute of Stem Cell Research, Ingolstädter Landstr. 1, 85764 Neuherberg/Munich, Germany
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22
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Morphogenic Signaling in Neurons Via Neurotransmitter Receptors and Small GTPases. Mol Neurobiol 2007; 35:278-87. [DOI: 10.1007/s12035-007-0023-0] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Revised: 11/30/1999] [Accepted: 12/08/2006] [Indexed: 01/21/2023]
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23
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Kvachnina E, Liu G, Dityatev A, Renner U, Dumuis A, Richter DW, Dityateva G, Schachner M, Voyno-Yasenetskaya TA, Ponimaskin EG. 5-HT7 receptor is coupled to G alpha subunits of heterotrimeric G12-protein to regulate gene transcription and neuronal morphology. J Neurosci 2006; 25:7821-30. [PMID: 16120784 PMCID: PMC6725246 DOI: 10.1523/jneurosci.1790-05.2005] [Citation(s) in RCA: 151] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The neurotransmitter serotonin (5-HT) plays an important role in the regulation of multiple events in the CNS. We demonstrated recently a coupling between the 5-HT4 receptor and the heterotrimeric G13-protein resulting in RhoA-dependent neurite retraction and cell rounding (Ponimaskin et al., 2002). In the present study, we identified G12 as an additional G-protein that can be activated by another member of serotonin receptors, the 5-HT7 receptor. Expression of 5-HT7 receptor induced constitutive and agonist-dependent activation of a serum response element-mediated gene transcription through G12-mediated activation of small GTPases. In NIH3T3 cells, activation of the 5-HT7 receptor induced filopodia formation via a Cdc42-mediated pathway correlating with RhoA-dependent cell rounding. In mouse hippocampal neurons, activation of the endogenous 5-HT7 receptors significantly increased neurite length, whereas stimulation of 5-HT4 receptors led to a decrease in the length and number of neurites. These data demonstrate distinct roles for 5-HT7R/G12 and 5-HT4R/G13 signaling pathways in neurite outgrowth and retraction, suggesting that serotonin plays a prominent role in regulating the neuronal cytoarchitecture in addition to its classical role as neurotransmitter.
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MESH Headings
- Animals
- Cells, Cultured
- GTP-Binding Protein alpha Subunits, G12-G13/genetics
- GTP-Binding Protein alpha Subunits, G12-G13/metabolism
- Mice
- NIH 3T3 Cells
- Neurites/physiology
- Neurons/cytology
- Neurons/metabolism
- Receptors, G-Protein-Coupled/agonists
- Receptors, G-Protein-Coupled/antagonists & inhibitors
- Receptors, G-Protein-Coupled/genetics
- Receptors, G-Protein-Coupled/metabolism
- Receptors, Serotonin/genetics
- Receptors, Serotonin/metabolism
- Serotonin/physiology
- Serotonin Antagonists/pharmacology
- Signal Transduction/physiology
- Transcription, Genetic/physiology
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Affiliation(s)
- Elena Kvachnina
- Abteilung Neurologie und Sinnesphysiologie, Physiologisches Institut, Universität Göttingen, Humboldtallee 23, 37073 Göttingen, Germany
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24
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Zhu S, Liu L, Korzh V, Gong Z, Low BC. RhoA acts downstream of Wnt5 and Wnt11 to regulate convergence and extension movements by involving effectors Rho Kinase and Diaphanous: Use of zebrafish as an in vivo model for GTPase signaling. Cell Signal 2006; 18:359-72. [PMID: 16019189 DOI: 10.1016/j.cellsig.2005.05.019] [Citation(s) in RCA: 82] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2005] [Accepted: 05/06/2005] [Indexed: 01/09/2023]
Abstract
Gastrulation shapes the early embryos by forming three germ layers, ectoderm, mesoderm and endoderm. In vertebrates, this process requires massive cell rearrangement including convergence and extension (CE) movements that involve narrowing and lengthening of embryonic tissues as well as cell elongation. Such polarization and movements require precise reorganization and regulation of the cytoskeleton network and cell adhesion. Rho small GTPases are key regulators for dynamic actin cytoskeleton. However, the signaling mechanisms underlying their functions in CE remain to be further elucidated. We have cloned the zebrafish Danio rerio rhoA and by capitalizing on the specific functional knockdown using morpholinos against rhoA and the availability of CE mutants defective in Wnt signaling, we showed that rhoA morphants were reminiscent to noncanonical wnt mutants with serious disruption in CE movements. Injection of rhoA mRNA effectively rescued such defects in wnt5 and wnt11 mutants. Furthermore, CE defects in rhoA knockdown or wnt mutants can be suppressed through functional bypass after ectopic expression of the two mammalian Rho effectors, the Rho kinase and Diaphanous (mDia). These results provide the first evidence that the RhoA in vivo acts downstream of Wnt5 and Wnt11 to effect, without affecting cell fates, on the CE movements in zebrafish embryos. Significantly, it elicits such effect via both effectors, Rho kinase and Dia. These findings also support the versatility of the zebrafish as a model to further investigate the roles of various classes of small GTPases in regulating cell dynamics in vivo.
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Affiliation(s)
- Shizhen Zhu
- Cell Signaling and Developmental Biology Laboratory, National University of Singapore, 14 Science Drive 4, Singapore 117543, The Republic of Singapore
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25
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Hand R, Bortone D, Mattar P, Nguyen L, Heng JIT, Guerrier S, Boutt E, Peters E, Barnes AP, Parras C, Schuurmans C, Guillemot F, Polleux F. Phosphorylation of Neurogenin2 specifies the migration properties and the dendritic morphology of pyramidal neurons in the neocortex. Neuron 2006; 48:45-62. [PMID: 16202708 DOI: 10.1016/j.neuron.2005.08.032] [Citation(s) in RCA: 260] [Impact Index Per Article: 14.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2004] [Revised: 05/04/2005] [Accepted: 08/19/2005] [Indexed: 11/16/2022]
Abstract
The molecular mechanisms specifying the dendritic morphology of different neuronal subtypes are poorly understood. Here we demonstrate that the bHLH transcription factor Neurogenin2 (Ngn2) is both necessary and sufficient for specifying the dendritic morphology of pyramidal neurons in vivo by specifying the polarity of its leading process during the initiation of radial migration. The ability of Ngn2 to promote a polarized leading process outgrowth requires the phosphorylation of a single tyrosine residue at position 241, an event that is neither involved in Ngn2 direct transactivation properties nor its proneural function. Interestingly, the migration defect observed in the Ngn2 knockout mouse and in progenitors expressing the Ngn2(Y241F) mutation can be rescued by inhibiting the activity of the small-GTPase RhoA in cortical progenitors. Our results demonstrate that Ngn2 coordinates the acquisition of the radial migration properties and the unipolar dendritic morphology characterizing pyramidal neurons through molecular mechanisms distinct from those mediating its proneural activity.
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MESH Headings
- Age Factors
- Animals
- Basic Helix-Loop-Helix Transcription Factors/metabolism
- Blotting, Western/methods
- Cell Count/methods
- Cell Movement/physiology
- Cells, Cultured
- Chickens
- Cloning, Molecular/methods
- Dendrites/physiology
- Electrophoresis, Gel, Pulsed-Field/methods
- Electroporation/methods
- Embryo, Mammalian
- Embryo, Nonmammalian
- Female
- Fluorescent Antibody Technique/methods
- Gene Expression Regulation, Developmental/physiology
- Green Fluorescent Proteins/metabolism
- Humans
- In Vitro Techniques
- Male
- Mice
- Microscopy, Confocal/methods
- Microtubule-Associated Proteins/metabolism
- Models, Biological
- Neocortex/cytology
- Neocortex/embryology
- Neocortex/metabolism
- Nerve Tissue Proteins/metabolism
- Phosphorylation
- Pregnancy
- Pyramidal Cells/cytology
- Pyramidal Cells/physiology
- Sequence Alignment
- Stem Cells/physiology
- Time Factors
- Tubulin/metabolism
- Tyrosine/metabolism
- rhoA GTP-Binding Protein/metabolism
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Affiliation(s)
- Randal Hand
- Department of Phamacology, Neuroscience Center, University of North Carolina, Chapel Hill, North Carolina 27599, USA
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26
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Decourt B, Bouleau Y, Dulon D, Hafidi A. Expression analysis of neuroleukin, calmodulin, cortactin, and Rho7/Rnd2 in the intact and injured mouse brain. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2005; 159:36-54. [PMID: 16051374 DOI: 10.1016/j.devbrainres.2005.06.013] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/09/2004] [Revised: 06/03/2005] [Accepted: 06/15/2005] [Indexed: 12/18/2022]
Abstract
Subtracted cDNA libraries from the mouse developing inferior colliculus were previously constructed between postnatal day (P) 6 and 10. In the P10-P6 subtracted library, neuroleukin, calmodulin I, cortactin, and Rho7 were identified. The goal of the present study was to analyze their distribution, at the mRNA and protein levels, in both the adult and the developing mouse brain. The four molecules showed a wide expression throughout the brain, with a neuronal-enriched localization in structures such as the cortex, the hippocampus, the cerebellum, and the inferior colliculus. The level of expression of their corresponding mRNAs increased during brain postnatal development. The expression of these molecules was also investigated 2 weeks after a mechanical lesion in the adult cerebral cortex. Neuroleukin and cortactin were found to be expressed by reactive astrocytes, while there were no changes in the expression of calmodulin and Rho7. The expression of neuroleukin, calmodulin, cortactin, and Rho7 is discussed in the context of their putative role in the maturation of the brain and in the axonal regeneration process.
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Affiliation(s)
- Boris Decourt
- EA3665, Laboratoire de Biologie Cellulaire et Moléculaire de l'Audition, Université Victor Segalen Bordeaux 2, Hôpital Pellegrin, Bâtiment PQR 3, 33076 Bordeaux, France
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27
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Meyer DK, Fischer C, Becker U, Göttsching I, Boutillier S, Baermann C, Schmidt G, Klugbauer N, Leemhuis J. Pituitary Adenylyl Cyclase-activating Polypeptide 38 Reduces Astroglial Proliferation by Inhibiting the GTPase RhoA. J Biol Chem 2005; 280:25258-66. [PMID: 15870074 DOI: 10.1074/jbc.m501630200] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Pituitary adenylyl cyclase-activating polypeptide 38 (PACAP38) plays an important role in the proliferation and differentiation of neural cells. In the present study, we have investigated how PACAP38 inhibits the proliferation of cultured neocortical astroglial cells. When applied to synchronized cells during the G(1) phase of the cell cycle, PACAP38 diminished the subsequent nuclear uptake of bromodeoxyuridine. When applied for 2 days, it reduced the cell number. PACAP38 did not exert its antiproliferative effect by activating protein kinase A. It also did not reduce the activity of mitogen-activated protein kinases essential for G(1) phase progression. Instead, PACAP38 acted on a member of the Rho family of small GTPases. It reduced the activity of RhoA as was shown with a Rhotekin pull-down assay. The decrease in endogenous RhoA activity induced by treatment of the cells with C3 exotoxin or by expression of dominant negative RhoA also reduced the nuclear uptake of bromodeoxyuridine. In contrast, expression of constitutively active RhoA prevented the effect of PACAP38. Our data show a novel signal transduction pathway by which the neuropeptide influences cell proliferation.
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Affiliation(s)
- Dieter K Meyer
- Institut für Experimentelle und Klinische Pharmakologie und Toxikologie, Zentrum für Neurowissenschaften, Albert-Ludwigs-Universität, D-79104 Freiburg, Germany.
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28
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Ma XM, Huang JP, Eipper BA, Mains RE. Expression of Trio, a member of the Dbl family of Rho GEFs in the developing rat brain. J Comp Neurol 2005; 482:333-48. [PMID: 15669055 DOI: 10.1002/cne.20404] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Trio, a member of the Dbl family of guanine nucleotide exchange factors (GEFs), has a series of spectrin repeats, two GEF domains, protein interaction domains, and a putative kinase domain, potentially important in neuronal axon guidance and cell migration. Most knowledge about Trio is based on studies of Caenorhabditis elegans and Drosophila, while the function of Trio in vertebrates is unclear. The aim of these experiments was to establish the patterns of Trio expression in the postnatal rat brain. During postnatal (P) development, high levels of Trio mRNA are found in the cerebral cortex, hippocampus, thalamus, caudate/putamen, and olfactory bulb, with lower levels in the septal nucleus, nucleus accumbens, amygdala, and hypothalamus. Except for the cerebellum, Trio mRNA in major brain areas is highest at P1, decreasing gradually during development, with low but detectable levels at P30. In P14 cerebral cortex, pyramidal neurons with strongly staining soma and dendrites are observed primarily in layer 5. In hippocampus, strong staining is observed in pyramidal neurons, granule cells, and isolated interneurons. Cerebellar Purkinje neurons exhibit intense staining in the soma and in extensive dendritic arbors at P7 and P14. Levels of Trio mRNA and the intensity of Trio immunostaining in cerebellar Purkinje cells increase from P1 to P30. Consistent with the in situ hybridization pattern, Western blot analyses show that Trio levels in the hippocampus and cortex are high at P1, decreasing until P30. The data suggest that Trio plays an important role during neuronal development.
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Affiliation(s)
- Xin-Ming Ma
- University of Connecticut Health Center, Department of Neuroscience, MC-3401, 263 Farmington Ave., Farmington, Connecticut 06030, USA.
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29
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Abstract
Ras-related GTPases of the Rho family, such as RhoA and RhoB, are well-characterised mediators of morphological change in peripheral tissues via their effects on the actin cytoskeleton. We tested the hypothesis that Rho family GTPases are involved in synaptic transmission in the CA1 region of the hippocampus. We show that GTPases are activated by synaptic transmission. RhoA and RhoB were activated by low frequency stimulation, while the induction of long-term potentiation (LTP) by high frequency stimulation was associated with specific activation of RhoB via NMDA receptor stimulation. This illustrates that these GTPases are potential mediators of synaptic transmission in the hippocampus, and raises the possibility that RhoB may play a role in plasticity at hippocampal synapses during LTP.
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Affiliation(s)
- E M O'Kane
- Division of Neuroscience and Biomedical Systems, Institute of Biomedical and Life Sciences, West Medical Building, University of Glasgow, Glasgow G12 8QQ, Scotland, UK
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30
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Chauhan S, Kunz S, Davis K, Roberts J, Martin G, Demetriou MC, Sroka TC, Cress AE, Miesfeld RL. Androgen control of cell proliferation and cytoskeletal reorganization in human fibrosarcoma cells: role of RhoB signaling. J Biol Chem 2003; 279:937-44. [PMID: 14576147 PMCID: PMC2735393 DOI: 10.1074/jbc.m311325200] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
We recently generated an HT-1080-derived cell line called HT-AR1 that responds to dihydrotestosterone (DHT) treatment by undergoing cell growth arrest in association with cytoskeletal reorganization and induction of neuroendocrine-like cell differentiation. In this report, we show that DHT induces a dose-dependent increase in G0/G1 growth-arrested cells using physiological levels of hormone. The arrested cells increase in cell size and contain a dramatic redistribution of desmoplakin, keratin 5, and chromogranin A proteins. DHT-induced cytoskeletal changes were also apparent from time lapse video microscopy that showed that androgen treatment resulted in the rapid appearance of neuronal-like membrane extensions. Expression profiling analysis using RNA isolated from DHT-treated HT-AR1 cells revealed that androgen receptor activation leads to the coordinate expression of numerous cell signaling genes including RhoB, PTGF-beta, caveolin-2, Egr-1, myosin 1B, and EHM2. Because RhoB has been shown to have a role in tumor suppression and neuronal differentiation in other cell types, we investigated RhoB signaling functions in the HT-AR1 steroid response. We found that steroid induction of RhoB was DHT-specific and that newly synthesized RhoB protein was post-translationally modified and localized to endocytic vesicles. Moreover, treatment with a farnesyl transferase inhibitor reduced DHT-dependent growth arrest, suggesting that prenylated RhoB might function to inhibit HT-AR1 cell proliferation. This was directly shown by transfecting HT-AR1 cells with RhoB coding sequences containing activating or dominant negative mutations.
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Affiliation(s)
- Sanjay Chauhan
- Department of Biochemistry and Molecular Biophysics, The University of Arizona, Tucson, Arizona 85721
| | - Susan Kunz
- Department of Biochemistry and Molecular Biophysics, The University of Arizona, Tucson, Arizona 85721
| | - Kelli Davis
- Department of Biochemistry and Molecular Biophysics, The University of Arizona, Tucson, Arizona 85721
| | - Jordan Roberts
- Department of Molecular and Cellular Biology, The University of Arizona, Tucson, Arizona 85721
| | - Greg Martin
- Department of Biochemistry and Molecular Biophysics, The University of Arizona, Tucson, Arizona 85721
| | - Manolis C. Demetriou
- Department of Cell Biology and Anatomy, The University of Arizona, Tucson, Arizona 85721
- The Arizona Cancer Center, The University of Arizona, Tucson, Arizona 85721
| | - Thomas C. Sroka
- Department of Cell Biology and Anatomy, The University of Arizona, Tucson, Arizona 85721
- The Arizona Cancer Center, The University of Arizona, Tucson, Arizona 85721
| | - Anne E. Cress
- Department of Molecular and Cellular Biology, The University of Arizona, Tucson, Arizona 85721
- Department of Cell Biology and Anatomy, The University of Arizona, Tucson, Arizona 85721
- The Arizona Cancer Center, The University of Arizona, Tucson, Arizona 85721
| | - Roger L. Miesfeld
- Department of Biochemistry and Molecular Biophysics, The University of Arizona, Tucson, Arizona 85721
- Department of Molecular and Cellular Biology, The University of Arizona, Tucson, Arizona 85721
- To whom correspondence should be addressed: Dept. of Biochemistry and Molecular Biophysics, University of Arizona, Tucson, AZ 85721. Tel.: 520-626-2343; Fax: 520-621-1697; E-mail:
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31
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O'Kane EM, Stone TW, Morris BJ. Distribution of Rho family GTPases in the adult rat hippocampus and cerebellum. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2003; 114:1-8. [PMID: 12782387 DOI: 10.1016/s0169-328x(03)00121-9] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/27/2022]
Abstract
Small GTPases are monomeric guanine nucleotide binding proteins of 20-25 kDa mass. Rho GTPases belong to the Ras superfamily of small GTPases. The small GTPases of the Rho family have been shown to participate in the organisation of the actin cytoskeleton and signal transduction pathways leading to gene transcription. Recent evidence suggests that Rho family GTPases may play an important role in synaptic communication in the brain, and particularly in synatic plasticity. In this study the distribution of RhoA, RhoB, RhoG, Cdc42, and Rac1 was investigated in hippocampal and cerebellar tissue of adult rat brain using immunohistochemical techniques. Previous studies suggest that distribution of Rho family mRNA is uniform throughout these structures. Here we provide evidence for differences in expression of these proteins between different regions of the hippocampus, and between the molecular and granular layers in the cerebellum. These differences may prove important with regard to the physiological functions of Rho family GTPases.
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Affiliation(s)
- E M O'Kane
- Institute of Biomedical and Life Sciences, Division of Neuroscience and Biomedical Systems, University of Glasgow, Glasgow G12 8QQ, UK.
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32
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Abstract
Nervous system development is reliant on neuronal pathfinding, the process in which axons are guided to their target cells by specific extracellular cues. The ability of neurons to extend over long distances in response to environmental guidance signals is made possible by the growth cone, a highly motile structure found at the end of neuronal processes. Growth cones detect directional cues and respond with either attractive or repulsive movements. The motility of growth cones is dependent on rapid reorganization of the actin cytoskeleton, presumably mediated by actin-associated proteins under the control of incoming guidance signals. This article reviews how one such family of proteins, the ADF/cofilins, are emerging as key regulators of growth cone actin dynamics. These proteins are essential for rapid actin turnover in a variety of different cell types. ADF/cofilins are heavily co-localized with actin in growth cones and are necessary for neurite outgrowth. ADF/cofilin activities are regulated through reversible phosphorylation by LIM kinases and slingshot phosphatases. LIM kinases are downstream effectors of the Rho GTPases Rho, Rac, and Cdc42. Growing evidence suggests that extracellular guidance cues may locally alter actin dynamics by regulating the activity of LIM kinase and ADF/cofilin phosphatases via the Rho GTPases. In this way, ADF/cofilins and their upstream effectors may be pivotal to our understanding of how guidance information is translated into physical alterations of the growth cone actin cytoskeleton.
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Affiliation(s)
- Ravine A Gungabissoon
- Department of Biochemistry and Molecular Biology and Molecular, Cellular and Integrative Neuroscience Program, Colorado State University, Fort Collins, Colorado 80523-1870, USA
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33
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Foletta VC, Brown FD, Young WS. Cloning of rat ARHGAP4/C1, a RhoGAP family member expressed in the nervous system that colocalizes with the Golgi complex and microtubules. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2002; 107:65-79. [PMID: 12414125 DOI: 10.1016/s0169-328x(02)00448-5] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
The Rho GTPase family of intracellular molecular switches control multiple cellular functions via the regulation of the actin cytoskeleton. Increasing evidence implicates a critical involvement of these molecules in the nervous system, particularly during neuronal migration and polarity, axon and growth cone guidance, dendritic arborization and synaptic formation. However, the molecules regulating Rho GTPase activities in the nervous system are less known. Here, we present the cloning of rat ARHGAP4, a member of the Rho GTPase activating protein family, and also demonstrate its close linkage to the vasopressin 2 receptor gene. In vitro, recombinant ARHGAP4 stimulated the GTPase activity of three members of Rho GTPases, Rac1, Cdc42 and RhoA. ARHGAP4 mRNA expression was observed in multiple tissues with marked expression throughout the developing and adult nervous systems. On closer analysis of protein levels, ARHGAP4 was significantly restricted to specific regions in the nervous system. These included the stratum lucidem in the CA3 area of the hippocampus, neuronal fibers in the ventral region of the brainstem and striatum, and in the cerebellar granule cells. Subcellularly, endogenous ARHGAP4 expression localized to the Golgi complex and could redistribute to the microtubules, for example during mitosis. In addition, distinct protein expression was observed in the tips of differentiating neurites of PC12 cells. Collectively, these results demonstrate that ARHGAP4 is more widely expressed than previously thought but potentially possesses specialized activity in regulating members of the Rho GTPase family in specific cellular compartments of the nervous system.
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Affiliation(s)
- Victoria C Foletta
- Section on Neural Gene Expression, The National Institute of Mental Health, National Institutes of Health, Bethesda, MD 20892, USA
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34
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Ishikawa Y, Katoh H, Nakamura K, Mori K, Negishi M. Developmental changes in expression of small GTPase RhoG mRNA in the rat brain. BRAIN RESEARCH. MOLECULAR BRAIN RESEARCH 2002; 106:145-50. [PMID: 12393274 DOI: 10.1016/s0169-328x(02)00413-8] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
We have recently reported that RhoG, a member of Rho family small GTPases, is involved in neurite outgrowth in cultured neuronal cells. Here, we report the expression of RhoG mRNA in the developing rat brain by in situ hybridization analysis. At embryonic day 16, RhoG expression was observed throughout the ventricular zone, but was down-regulated in the region at birth. On the other hand, RhoG expression at postnatal day 20 was highly enriched in white matter tracts, including the corpus callosum, the anterior commissure, and the cerebellar white matter, and double-labeling experiments demonstrated that major RhoG-expressing cells in white matter tracts were oligodendrocytes. These results suggest distinct pre- and postnatal roles of RhoG in the development of the central nervous system.
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Affiliation(s)
- Yukio Ishikawa
- Laboratory of Molecular Neurobiology, Graduate School of Biostudies, Kyoto University, Sakyo-ku, Japan
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35
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Laplante I, Paquin J, Béliveau R. RhoB expression is induced after the transient upregulation of RhoA and Cdc42 during neuronal differentiation and influenced by culture substratum and microtubule integrity. BRAIN RESEARCH. DEVELOPMENTAL BRAIN RESEARCH 2001; 129:157-68. [PMID: 11506860 DOI: 10.1016/s0165-3806(01)00197-3] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
RhoGTPases are important intracellular signalling switches in the regulation of cytoskeleton organization. They likely have an important role in ontogenesis because cytoskeletal rearrangements accompany cell differentiation and specialization. Western blotting showed that protein expression of RhoA, RhoB and Cdc42 RhoGTPases dramatically increased, in a programmed manner, during neuronal differentiation of P19 mouse embryonal carcinoma cells with retinoic acid. RhoA and Cdc42 expression were sequentially upregulated and peaked during the commitment period while that of RhoB was induced in post-mitotic neurons. Although RhoB had a higher expression on matrices allowing cell spreading and neurite elongation, it was distributed throughout cell volume by immunocytofluorescence and associated with various cell compartments by centrifugal subfractionation, suggesting a role not restricted at neurites at this stage of differentiation. RhoA and Cdc42 were mainly cytosolic and RhoB particulate in the P19 cell model. Treatment of cells with cytoskeleton disruptors showed that poisons of microtubules but not of actin filaments or neurofilaments increased the cytosolic level of RhoB. The results indicate that RhoA, Cdc42 and RhoB must intervene at specific stages of neuronal development and there exists a relationship between RhoB expression/distribution, the microtubule network and the extracellular matrix during this process.
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Affiliation(s)
- I Laplante
- Laboratoire de Neuroendocrinologie développementale, Département de chimie et de biochimie, Université du Québec à Montréal, C.P. 8888, Succursale Centre-ville, Montreal, Québec, H3C 3P8 Canada
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36
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Terashima T, Yasuda H, Terada M, Kogawa S, Maeda K, Haneda M, Kashiwagi A, Kikkawa R. Expression of Rho-family GTPases (Rac, cdc42, RhoA) and their association with p-21 activated kinase in adult rat peripheral nerve. J Neurochem 2001; 77:986-93. [PMID: 11359863 DOI: 10.1046/j.1471-4159.2001.00336.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
To clarify the presence of the Rho family of small GTPases p21-activated kinase (pak) signaling pathway in the PNS, we have examined their expression, the association between the small GTPases and pak and the pak kinase activity in the PNS using immunoblot analysis, immunohistochemistry, co-immunoprecipitation study, and in vitro kinase assay. Immunoblot analysis showed the expression of Rac, cdc42, RhoA and pak in the dorsal root ganglion (DRG) and sciatic nerve. The localization of these proteins in the DRG neurons and axons and Schwann cells of the sciatic nerve was confirmed by immunohistochemistry. Co-immunoprecipitation studies indicated the in vivo associations of pak with Rac and cdc42, but not with RhoA, in both the DRG and sciatic nerve. The autophosphorylation of pak and phosphorylation of histone H4 by pak were also found in the DRG and sciatic nerve as well as in the CNS. These results suggest that the Rac/cdc42-pak signaling pathway exists and functions in the PNS and may mediate some intracellular signals.
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Affiliation(s)
- T Terashima
- The Third Department of Medicine, Shiga University of Medical Science, Otsu, Shiga, Japan
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